Engine control circuit and switch mechanism



June 13, 1961 R. H. VOlGT 2,988,079

ENGINE CONTROL CIRCUIT AND SWITCH MECHANISM Filed Oct. 15, 1958 4 Sheets-Sheet 1 WIIIIIFIIIIIF will ROBERT H. VOIGHT INVENTOR.

BYWMW ATTORNEY June 13, 1961 H. VOlGT 2,988,079

ENGINE CONTROL CIRCUIT AND SWITCH MECHANISM Filed Oct. 13, 1958 4 Sheets-Sheet 2 ROBERT H. YOIGHT -INVENTOR.

ATTORNEY June 13, 1961 vo 2,988,079

ENGINE CONTROL CIRCUIT AND SWITCH MECHANISM Filed Oct. 13, 1958 4 Sheets-Sheet 3 ROBERT H. VOI GHT INVENTOR.

R. H. VOIGT June 13, 1961 ENGINE CONTROL CIRCUIT AND SWITCH MECHANISM Filed Oct. 13, 1958 4 Sheets-Sheet 4 Ill FIG 3 LN I n ROBERT H. VOIGHT Fl 6 |O INVENTOR.

ATTORNEY United States Pate I 2,988,079 ENGINE CONTROL CIRCUIT AND SWITCH MECHANISM Robert H. Voigt, Milford, Mich. Filed Oct. 13, 1958, Ser. No. 767,028 20 Claims. (Cl. 123-179) This invention relates to an electrical control circuit and switch mechanism for starting and maintaining the operation of an internal combustion engine and particularly the electric fuel pump thereof and for stopping the same upon failure of the engine lubricant pressure.

This application is a continuation in part of my application Serial Number 739,336 filed June 2, 1958, now Patent No. 2,949,906 for Engine Control System and Apparatus.

It is an object of the invention to provide a thermally responsive, time delay switch mechanism for energizing the starting motor of an engine, which mechanism is constructed so as to compensate for the effects of ambient air temperature.

Another object of the invention is to provide a starting switch mechanism which is capable of controlling electric currents of relatively high amperage as well as smaller currents.

Still another object of the invention is to provide a switch mechanism of the type described which operates with a snap action.

A further object of the invention is to provide a switch mechanism which will maintain the closing delay time relatively constant when exposed to an ambient temperature range of from 65 degrees F. below zero to 350 degrees F. above zero.

These and other objects will become apparent from a study of this specification and the drawings which are attached hereto, made a part hereof and in which:

FIGURE 1 is a schematic diagram of the circuit and components thereof.

FIGURE 2 is a sectional elevation of the switch mechanism taken substantially on the line 2--2 of FIGURE 4 and showing the fuel pump switch.

FIGURE 3 is a sectional elevation of the switch mechanism taken substantially on the line 3-3 of FIGURE 4 showing the thermally responsive switch and associated mechanism.

FIGURE 4 is a plan view of FIGURE 2 with the fluid pressure device removed.

FIGURES 5, 6 and 7 are isometric views of bimetal element showing the displacement of the parts thereof under various ambient temperatures.

FIGURE 8 is an elevation of the time delay switch and its actuating mechanism.

FIGURE 9 is an expanded isometric view of the thermostatic switch structure.

FIGURE 10 is a plan view with parts broken away to show the connection between the fulcrum lever, line and spring.

FIGURE 11 is an expanded isometric view of a modified form of the thermostatic switch structure.

WIRING DIAGRAM FIGURE 1 Referring to FIGURE 1, the numeral 1 indicates the usual storage battery which is grounded at 3 and which supplies current through wire to the usual ignition switch 7. A wire 9 connects the output side of this switch to the ignition apparatus indicated generally by 11.

A wire 13 connects the output side of this switch to one fixed contact 15 of a normally open, manually openated starting switch 17 which may be of any desired type. This switch is often incorporated in the ignition switch. The other fixed contact 19 of this switch is connected by wire 21 to a terminal post 23 of the switch mechanism which is indicated generally by 25.

The switch mechanism comprises three separate devices incorporated in a unitary structure. It includes a relay indicated generally by 27 which comprises a coil 29, a pair of normally open contacts 31 mounted on spring type switch blades 55 and 57, which are connected in electrical communication with terminal posts 59 and 61 respectively, and an armature 33 which actuates a plunger 133 to close switch 31. The mechanism also includes a thermostat or thermal switch indicated generally by 35. This switch has a bimetal thermoresponsive unit 39 comprising a resistance heating coil 37 wound on a bimetal blade 140, a switch mechanism 41, which includes a movable switch blade one end of which is connected electrically to post 23 by bus wire 168 and which has, at thev free end, a contact A which normally engages a contact D in series with the heating coil 37 which is connected to ground at 54, and a shorting bar B which is normally lifted from a pair of contacts C, one of which is connected to terminal post 23 and the other to post 40. The third device is a fluid pressure responsive device indicated generally by 43 which comprises a diaphragm 45 forming a wall of pressure chamber 47 which has a tube 49 connected to the pressure side of the oil pump 50, which is driven by the engine, and a pushrod 46, disposed for actuation by the diaphragm and for contact with switch blade 55 to close switch 31 or hold it closed, as the diaphragm expands under pressure.

A wire 51 connected to terminal 23 is connected to one end of relay coil 29. The other end of this coil is grounded at 54.

One terminal post 59 is connected by a wire 63 to the starter switch contact 15 or otherwise directly to the output of switch 7 while the other post 61 is connected by wire 65 to one side of the fuel pump motor 67 while the other side is grounded at 69.

A starting motor relay 71 comprises a pair of coils 73A and 73B. The former is connected to ground 87 through the starting motor 85 and the latter is connected to ground at 91. The relay also includes a pair of fixed contacts 75, a movable contact 77 adapted to bridge contacts 75 and an armature 79. Contacts 75, 77 are normally open but are closed when the coils 73A and 73B are energized so as to actuate the armature. A wire 81 connects one of the contacts 75 to the battery wire 5 ahead of the ignition switch 7 and a wire 83 connects the other contact 75 to one side of the starting motor which is grounded at 87.

The input sides of coils 73A and 73B are connected to terminal post 40 by wire 89.

The fuel conduit 93 connects the discharge of the fuel pump 95 with the float chamber of the engine carburetor or other fuel charging device (not shown).

CIRCUIT OPERATION While the detailed construction and operation of the switch mechanism will be set forth below, the general operation of the circuit and its components will first be explained.

In my prior application, mentioned above, the current for energizing the relay 71 is passed through the bimetal element 39 and the amperage which it is practically feasible to pass through this element is limited.

In the type of starting system shown in the instant application, it will be noted that both coils 73A and 7313 must be energized and the required current, especially the initial surge, may reach values on the order of amperes. This value drops when the relay contacts 75, 77 close. However, since this surge is experienced each time the starting switch 17 is closed, it is deemed advisable to provide a structure which will protect the bimetal element from such current values.

This application further contemplates means for providing a substantially stable time delay period between the energization of the fuel pump and the energization of the starting motor by the provision of ambient temperature compensating means. The transmission of high amperages through the bimetal element would also complicate this structure. The circuit and switch mechanism disclosed herein by-passes heavy amperage current around the bimetal element and makes possible accurate, ambient temperature compensation in a simple practical manner.

The contacts A and D are normally closed as shown in FIGURES 1 and 8. When it is desired to start the engine, the ignition switch 7 is closed to energize the ignition system 11 and to connect the starting switch contact 15 with the battery.

The starting switch is then manually closed and held closed to extend battery current to terminal post 23, to relay coil 29 and to ground 54. A circuit is also closed from post 23, switch mechanism 41, contacts A and D, heater coil 37, and wire 17b to ground 54. As will be explained below, the heating time required to energize the bimetal element 39 to the reverse position, with contacts A and D open and contacts B and C closed, is substantially constant within an ambient temperature range of from 65 degrees F. below zero to 350 degrees F. above zero and the operation of the blade 1tlil112 of switch mechanism 41 in both directions is accomplished with a snap action.

The heating coil 37 begins to heat as soon as switch 17 is closed. Relay 27 also closes the switch 31 at once, to close the circuit from battery to fuel pump motor 67 through lines 5, 13, 63, switch 31 and line 65, to motor 67 and ground 69 and the fuel pump will start. This operation insures that the fuel pump motor will be supplied current under substantially full battery voltage to that all of the available power can be applied to start the motor.

This is an important feature because in cold weather, the motor 67 and pump 95 sometimes require near normal battery voltage on the initial start because of increased frictional loads imposed by cold bearings etc. The voltage and efliciency of the battery is usually reduced at low temperatures and if the heavy drain of the starting motor is imposed on the battery at a time when the fuel pump requires more than its usual starting voltage, the pump motor may not start and may thus contribute to a failure of the engine to start, if the fuel supply at the engine happens to be depleted.

The power requirements of the fuel pump, when it is running, are such that it is not likely to stall when the starting load is applied.

By energizing the fuel pump motor in advance of the starting motor, the operation of the fuel pump and an adequate supply of fuel at the carburetor will be assured under the most adverse temperature conditions, so that the starting of the engine will not be defeated for lack of fuel.

Heater coil 37, which was energized at the same time as relay coil 29, will heat the bimetal blade 144) (FIG. which Will warp and, after the interval of a few seconds, will snap the contacts B and C closed and open contacts A and D to deenergize the heating coil. switches attain this condition they will be held until the bimetal has cooled, whereupon the switches will snap back .to their original conditions. The time delay in restoring the switches is sufdcient to permit rather prolonged cranking if the engine without interruption by the opening of contacts B and C.

When the closure of contacts B and C occurs, the battery is connected through lines 5, 13, 21, post 23, contacts B and C, post 40, line 89, relay coil 73A, line 83, starting motor 85 to ground 57 and also from line 89 through coil 7313 to ground 91. .Thus both coils are energized and they draw a relatively large amperage cur- Once the 7 aeeanve 4 i 4 rent because the armature 79, in the type of starting system shown, not only closes contacts 75, 77 but must also engage the starting motor pinion with the flywheel. This imposes a heavy mechanical load on the armature and consequently the power requirement of the two coils is high, resulting in the high amperage surge mentioned above.

As soon as the contacts 75, 77 are closed, a circuit is set up from battery through lines 5, 81, contacts 75-77, line 83 to motor 85 and ground 37. When this occurs the amperage drawn by coil 73A drops materially and the reduced current flow through the coils 73A, 73B is adequate to hold the armature in the actuated position.

I Motor 85 cranks the engine and when the engine starts,

the starting switch 17 is released to break the circuits to the coils 73A, 73B and 29:. Relay 71 is deenergized as is relay 27. The switch contacts 31 are thus no longer held closed by the latter. However, when the engine is running, the oil pump 50 applies oil under pressure, through tube 49 and chamber 47, to the diaphragm 45 which moves pushrod 46 and blade 55 in a direction to hold or to reclose the switch 31, depending upon the value to which the oil pressure rises during cranking and immediately upon starting.

If this switch is still held. closed by the relay when dia phragm 45 acts, the diaphragm will cause blade 55 to follow blade 57 when the relay coil 29 is deenergized as described and the switch 31 will remain closed.

Should the switch 31 be, opened in response to the deenergization of coil 29 before the oil pressure has built up sufiiciently to cause blade 55 to follow blade 57 as rapidly as the latter is withdrawn, it will eventually be reclosed when the proper oil pressure is reached. Thus, a proper supply of fuel will be provided at the engine so long as the required oil pressure is maintained.

However should the oil pressure fall below the value required to hold the switch 31 closed, the switch will open and stop the fuel pump. When the fuel supply at the engine becomes exhausted, the engine will stop.

Further, should the engine stall for any reason while the ignition switch remains closed, the oil pressure will fall and the diaphragm 45 will yield to the diaphragm support disc 147 (described below) and permit switch 31 to open and stop the fuel pump. This prevents unnecessary drain on the battery, wear on the fuel pump and detrimental agitation and heating of the fuel in the tank.

Should the engine be stopped as the result of a collision or other accident, the stopping of the fuel pump, as described above, will prevent fuel from being pumped to the engine compartment to create a fire hazard or to aggravate a tire which may already have started.

SWITCH MECHANISM FIGURES 2, 3, 4, 8, 9 and 10 The preferred form of my switch apparatus, as shown particularly in FIGURES 2, 3 and 4, incorporates the relay 27, thermal switch 35 and the oil pressure responsive device 43 in a singlestructure. It comprises a fitting 49 which is connected to a dome 91 which has a peripheral flange 93. A body 95, having a cylindrical upper portion of larger diameter than the lower portion, is preferably molded of plastic material of a thermosetting type, capable of withstanding the temperatures and other conditions encountered in an engine compartment.

A disc like metal pressure plate 97 has its central portion dished downwardly toward a central, axial opening 99 and is surrounded by a fiat peripheral flange 101 adapted to seat on the upper end of the body.

The diaphragm 45 is preferably formed of sheet syn thetic rubber material which has a bursting strength of several hundred poundsrand does not deterioratematerially when exposed to hot lubricating oils. The diaphragm is' disposed between the flanges 93 and 101 which are clamped in sealing relation against the. diaphragm by a cover or ferrule 103. The ferrule is preferably generally cylindrical and has an internal diameter which fits slidingly over the top portion of the body 95 and has an inturned flange 105 at its upper end which overlies the top of flange 93.

The body has a downwardly facing shoulder 109 at the juncture of its upper and lower portions over which the lower end of the ferrule is crimped at 111. The ferrule is subjected to axial pressure prior to crimping so that it will hold the diaphragm compressed between the flanges 93 and 101. Dome 91 and the diaphragm define an oil pressure chamber 47.

A pair of diametrically opposed terminal posts 59, 61 (FIGS. 2 and 4) are molded as inserts in the body 95 and extend from the bottom thereof to the switch chamber or cavity 117 in the upper portion of the body. The lower portion of the body defines a solenoid chamber or cavity 119 which has its bottom end closed by a wall 121 but which communicates with the switch cavity.

The relay or solenoid assembly comprises the posts 59, 61, core 125, coil 29 fitted on the core, a coil backup washer 127 of insulating material and a grip nut 128 are mounted on the core. A solenoid support plate 129 extends outwardly over the posts 59, 61 and is riveted at one end to post 61. The core 125 is preferably projection welded to plate 129. A spacer bushing 113 of electrical insulating material is mounted on the reduced upper end portion of post 59' and has an axially downwardly extending flange 137 which extends through the other end of plate 129. A pushrod 133, of nonmagnetic material, is slidably mounted in the core 125 and carries at its lower end a ferrous metal disc armature 33. One magnetic circuit is thus formed from plate 129 through post 61, across a gap to the armature 33, across a second gap to core 125, all of which are of ferrous material, and back to the plate. A second circuit is established in a similar manner through post 59.

The switch 31 comprises upper and lower spring blades or leaves 55, 57 which are held in spaced, superposed re lation on the spacer 113. The leaf 57 is clamped between plate 129 and the shoulder 116 on the spacer and rests on pushrod 133 while the upper leaf 55 is clamped to the upper end of the spacer by a metal washer 131 which is riveted in place on the post 59. Thus, when switch 31 is closed, a circuit is formed from 59 through blade 55, switch 31, blade 57, plate 129' to post 61. The switch 31 is normally held open by the resilience of the blades.

It should also be noted that, as shown in FIGURE 3, the blade 55 is widest at the fixed end and tapers preferably uniformly, toward the free, contact bearing end. It has been found that such construction insures against breakage of the blade adjacent the spacer 113 and also renders the blade less responsive to vibration at the frequencies normally encountered in use, so that premature closure or chattering of the switch is minimized.

The ends of the blades 55, 57 opposite the contacts also extend into a vertical groove 115 in the body to insure the alignment of the blades and contacts at all times.

It will be seen that the pushrod 133 bears on the under side of blade 57 intermediate its ends and will bend it upwardly when the solenoid coil 29 is energized. The stroke of the pushrod is such as to force the contact 31, mounted on the free end of the blade, into pressure contact with the opposed contact 31 on blade 55 and hold the blade 57 slightly bowed.

Referring now to the diaphragm mechanism, a plunger 46 of insulating material such as vulcanized fiber is provided with a generally cylindrical head 139, a shank portion of lesser diameter than the head and a lower end portion of further reduced diameter so as to form with the shank, a shoulder 141. The lower end of the plunger enters a hole 143 located adjacent the free end of the blade 55 so that the shoulder will bear against the upper side of the blade. The plunger 46 and pushrod 133 are preferably disposed in axial alignment.

The head 139 passes freely through the opening in pressure plate 97 and is also provided with a threaded axial hole 145. A diaphragm support disc 147 which is centrally perforated, is mounted on the head of the plunger by means of a shoulder screw 149 which passes through the disc and is screwed into the hole 145. It is preferably also cemented therein. A stop 151, described below, limits the downward travel of the plunger by contact with the plate 97.

The support element 147 is an important element because it controls the actions of the switch in both the opening and closing directions, in response to the forces applied to the diaphragm by the oil pressure in chamber- 47 as was fully explained in my prior application.

The disc has a diameter about half that of the plate 97 and is normally held out of contact with the plate, as shown in FIGURE 2, by the resilience of blade 55, when there is no pressure in the chamber. As pressure is applied to the diaphragm, it will move the disc 147 downwardly until its lower, peripheral edge engages the dished portion of the pressure plate 97. As increasing pressure is applied to the diaphragm, a portion of the diaphragm will be supported by the plate and the remainder by the support disc 147, so that the disc will have its central portion bowed or dished downwardly as the pressure increases.

Thus, as explained in detail in my prior application, a small pressure increase, such as 3 psi. will close the major portion of the gap between the contacts of switch 31 but it requires double this pressure or more to close the remaining portion of the gap. Further movement of the plunger, after closing of the contacts 31 is limited by the stop 151 striking on plate 97 so that blade 55 is bowed downwardly a slight amount which is sufficient to hold the contacts under pressure regardless of the final oil pressure which may reach 40 p.s.i. or more.

I have found a disc 147 made of glass cloth impregnated with silicone resin, as set forth in my prior application, to be satisfactory in providing the desired switch control, thermal stability, moisture resistance and ability to stand the rigorous conditions to which it is subjected.

Since the pushrod 133 and plunger 46 act on the switch blades intermediate the free ends thereof and the support 113, the contacts will engage with a wiping action and will be kept clean thereby. The armature 33 will strike the end of core 125 to limit the upward stroke of pushrod 133 so that the flexure of blade 57 is limited to a slight upward bowing and the blade is not excessively strained.

THERMOSTATIC SWITCH MECHANISM Referring now to FIGURES 3 and 4, it will be seen that two additional binding posts 23 and 40 are also molded as inserts in the body and extend up into the chamber 117, to a level above the switch blade 55 where they terminate in upwardly facing contacts C which are disposed at the same level.

The thermostatic switch 35 comprises the snap action switch mechanism 41 and the thermostatic unit 39 (FIG- URES 3, 8 and 9). The switch mechanism comprises a cross-bar 100 having the relatively long contact or shorting bar B on its under side for bridging contacts C and the contact A on its upper side which cooperates with the contact D carried by the bridge 130.

Bar 100 is connected by spring arm 112 to cross-bar 102 to form a hollow rectangular structure. Bar 102 carries an actuating arm 116 which extends into the rectangle, and an aligning tab 104 which projects oppositely from, but is in alignment with arm 116 and projects into a vertical groove 106 in the body.

A screw 110 which enters a hole 108 in the blade and enters a tapped hole in the body, holds the blade in place on a flat box 108 of the body. An opening 134 return the bar 100 to-the initial position '(FIG. 8). movement in both directions is thus executed with a snap action and whichever set of contacts is closed is held closed by the spring.

spasms 7 is (forged-indexer .116 o permi passage of e pushro. 4

At each inner juncture of the arms 112 with the bar 1110 isformed a projection 114 (FIGS. 9 and 10). A tab 122, having shoulders 122', extends axially from the free end of arm 116. A link 118 is provided with horizontal slits 120 and 124 parallel to and adjacent the top and bottom of the link. Tab 122 and shoulders 122 are adapted to project through the slit 124 so that the link will lie against the end of arm 116 proper and will be held against lateral shifting by the shoulders 122 while the end of the tab projects through and beyond the link.

A U-shaped spring 126 has a pair of notches 128 formed in each edge on one side adjacent to and extending parallel to one bottom edge, to receive the projections 114. The left side of the spring 126 (FIGS. 9 and 10) therefore bears on the inner edge of cross-bar 100 which serves as a fulcrum upon which the spring may rock. A

slit 132 (FIG. 10) is formed centraly adjacent and parallel to the other bottom edge of the spring 126 and receives the tab 122 which projects through the link 118. That side of the spring rests upon the edges of the shoulders 122 which serve as a fulcrum upon which the spring may rock.

The entire blade 112-116 is preferably punched out of beryllium strip stock, whilethe link 118 is made of fiberglass filled silicone resin similar to that used for the disc 147 of the oil pressure mechanism.

The operation of this structure is shown in FIGURES 3 and 8. The latter figure shows the parts in the normal positions with contacts A and D closed. The link 118 is moved up and down by the central arm 140 of the bimetal element 39 as will be described below. As arm 140 is heated above ambient temperature, the link 118 is lifted and acts on actuator arm 116 so as to bend it upwardly. The tab 122, carries the right leg of spring 126 upwardly until arm 116 crosses to the other side of a position in which arm 116 and bar 1% are coplanar. The legs of the spring are compressed toward each other during this movement and when the center position is crossed, the legs fiy apart, forcing the bar 106 from a position with contacts A and D closed as shown in FIG- URE 8 to the FIGURE 3 position in which contacts C are bridged by shorting bar B. Since the spring is not fully expanded in either of the described positions, pressure will be continuously exerted by the spring on bar 1110 andarm 11650 as tomaintain the contacts closed, in

either position, with a predetermined pressure.

When the bimetal arm 140 cools to ambient temperature, the arm 116 will return to its initial position due to its inherent resilience and as it passes the position in which it is coplanar with bar 100, the spring 126 which has been recompressed by such motion, will expand and The As shown in FIGURES 3, 4 and 9, a pair of flat topped bosses 136 are formed in the body and the bridge 130 is mounted at each end on one of the bosses by a screw 138. The bridge, has a central, transverse, u shaped channel 130' and contact D is mounted on the bottom side of the channel portion.

The two piece bimetal element 39shown particularly ,in FIGURES 5 to 7 comprises a generally U-shaped bimetal piece comprising two parallel, coplanar and coextensive-arms 144, 146 which are connected by cross-piece 142. The other piece is generally T-shaped and comprises a head portion 148 which conforms to crss-piece 142 and the center arm 140 which extends parallel to and between arm 144, 146. As shown in FIGS, the arm 14 is offset at 1415' adjacent head portion 143 so that the arm j 140 will .be. coplanar with arms 144, 146. The cross-piece 14,2 and head 1.45am fastened together by rivets 164 to form a unitary structure.

The arms 144 and 146 are slightly longer than 140 and terminate in lateral projections 152 which are perforated at 154 to receive the bridge supporting screws 138. The projections lie between the bosses and the bridge. Arms 144 and 146 are each half the width of arm 140.

Arm 140 has a T-shaped tab 156 extending centrally from the free end thereof which is adapted to enter slit of link 11 8, which has less width than the cross portion of the tab so that after the tab is worked through the slit and the link is centered thereon, the link cannot escape from the tab.

The bimetal element 39 is shown by the full lines in FIGURE 5 with the arms disposed in a single plane. This is the condition of the element at its normal ambient temperature, which is the temperature at which it is manufaetured and the normal temperature may vary somewhat between difierent brands of bimetal stock.

The dashed line position of arm 14% illustrates how the arm will warp out of the plane of arms 144, 146 when it is heated above the normal ambient temperature while the arms 144 and 146 remain at the normal ambient temperature. This movement is utilized to move link 118 and switch mechanism from the FIGURE 8 to the'FIGURE 3 position as explained above.

FIGURE 6 illustrates, in full lines, the condition of the element 39 when all of it has been heated to a temperature above the normal, as will occur when the ambient temperature increases. Since the arms 144 and 146 are fixed to the body by bridge 13% at the end opposite to 1412, all of the arms will warp equally and upwardly about the fixed ends thereof with the result that the cross bars 142, 148 will rise but the free end of arm 14% will remain substantially in its initial position So that it does'not move relative to the switch actuating lever 116. Consequently there is no movement of this lever as the result of a general temperature rise of the entire element.

However when the central arm 14% is further heated, it will Warp further relative to the other arms as shown in dashed lines in FIGURE 6 so as to raise the link 118 and actuate arm 116 to the position of FIGURE 3 to close contacts B and C.

Similarly when the temperature of the entire element falls belowthe normal temperature, all of the arms will warp downwardly as shown in full lines in FIGURE 7. Again there will be no substantial displacement of the free end of arm relative to lever 116 until this arm is separately heated, in which case it will rise as indicated in dashed lines (FIG. 7) to move the lever 116 to close contacts B and C as described.

Thus the construction provides compensation for variations in ambient temperatures so that the time required for operation of the switch blade by the arm 14% when it is heated by the coil is substantially the same for any ambient temperature within the range in which the unit is intended to operate.

Further, irrespective of the existing ambient temperature, the same temperature rise of the arm 140 when heated by coil 37 will produce substantially the same amount of travel at the tree end of the arm and thus the movement imparted to the actuating arm 116 is substantially uniform and insures proper operation of the switch.

While the time required for heating and cooling the arm 14% will vary somewhat between extreme high and low ambient temperature conditions, .due to the heat loss between the heating coil and the surrounding air, this variation is of a minor nature and does not materially affect the operation of the device. There may be a slight additional time lag, under low temperature conditions, between starting the pump and energizing the starting motor but this variation is favorable rather than unfavorable since it increases the time afforded the pump to come up to speed. The lag is, however, measured in a fraction of a second and is not material.

The structure just defined makes possible the proper operation of the switch over a range of ambient temperatures from about 65 F. degrees below to about 350 F. degrees above zero.

Referring to FIGURE 9, it will be seen that the center arm 140 is also provided with a hole 158 through which the pushrod 46 passes. It is also provided with wrap of thin, electric insulating material, 160 such as tetrafluoroethylene tape .(Teflon).

A coil 37 of resistance wire is wound around the arm 140 over the tape. The wire is preferably provided with a double coating of Fiberglas. One end of the coil 37 (FIG. 3) is fastened in electrical contact with the arm 140 by a rivet 166 and the other end 170 is looped around but insulated from the center one of the rivets 164 which hold the parts of the bimetal element together. This lead is connected to the lower leg of a ground clip 54 (FIG. 2) which has a horizontal portion 174 which rests on the top edge of the body and an upwardly extending hook 176 which is hooked over the edge of plate 97 and is pinched between the support plate 97 and the sleeve 103 when the unit is assembled. The sleeve is grounded through the cap 91, connector 49 and piping. If desired, a separate ground lead may be connected to the sleeve or other part which is electrically connected thereto. Wire 162 from coil 29 is also attached to this clip.

The bus wire 168 (FIG. 4) connects terminal post 23 with the screw 110. As explained above, when the starting switch 17 is closed, the battery current will be extended to terminal post 23 which carries one contact C. Bus wire 164 extends current from post 23 to screw 110 and through switch blade 102, 112, 100 to contacts A and B.

When the engine is not being operated, the contacts A and D are held closed by the switch mechanism which occupies the position of FIGURE 8.

Accordingly when the starting switch 17 is closed, current will flow through 168, the switch blade, contacts A and D, bridge 130, arms 144, 146 and 140 of the bimetal element, rivet 166, heating coil 37, lead 170 and clip 54 to ground.

The central arm 140 of the bimetal element will therefore be heated by coil 37 and it will warp in the upward direction shown by dashed lines in FIGURES 5 to 7, relative to the other arms 144, 146, to raise link 118 and bend actuating arm 116 upwardly. This movement of the arm 116 raises one side of the U-spring 126 and tilts the spring toward the FIGURE 3 position. When arm 116 passes the coplanar position with respect to bar 100, the spring will snap the bar 100 to the FIGURE 3 position, opening contacts A and D and closing contacts B and C so that the current to the heater coil 37 is interrupted while the battery current is extended from contact C on terminal post 23 through shorting bar B to contact C on post 40. From 40 current passes to the solenoids 73A and B and the starting motor as described above to energize these devices.

When the heating coil is deenergized, it and the arm 140 will cool; the arm will return toward its initial position thereby depressing link 118 and lever 116. The latter shifts the U-spring 126 clockwise toward the FIGURE 8 position and when it reaches the over-center position, it will snap the switch 41 to its FIGURE 8 position to open contacts B and C and to close contacts A and D.

A time delay of three seconds between the energization of coil 37 and the closing of contacts B and C is preferred although of course the device may be designed to any suitable delay desired. The time required to open these contacts should be much greater than the closing time, because ample opportunity for cranking the engine should be provided. This period is on the order of five minutes in the structure disclosed. The switch will of course open somewhat more rapidly when the ambient temperature is at the low limit because the heat dissipation from I 10 the coil 37 and arm will be greater than when it is at the high limit.

it is immaterial that contacts B and C require a relatively long time to open because the circuit through them to the starting motor will be interrupted by manually releasing the starting switch 17 as soon as the engine starts.

As explained above, once the engine starts the fuel pump circuit, which has been held closed by the starting switch controlled solenoid 27 and switch 31, is now held closed by the oil pressure motor 43 and switch 31 independently of the starting switch so that the fuel pump will continue to run after switch 17 is opened.

In case the oil pressure does not rise rapidly enough to hold the fuel pump switch 31 closed, it will usually reclose it quickly. However, if the oil pressure fails to rise, the switch 31 will remain open and when the fuel supply in the carburetor is used up, the engine will stop. The same results will be attained if the engine stops for any reason.

MODIFIED FORM FIGURE 11 In the structure shown in FIGURE 11, the switch mechanism 41A has been altered slightly in that the switch blade is formed as a hollow rectangle having a projection 182 for guiding in the body slot 106. The actuating lever 184 is made of beryllium, is made separate from the switch blade and has one end coextensive with projection 182 and the other end 186 turned up to take the place of the link 118. Ear 186 preferably intersects 184 at an angle of about 97 to 99 degrees and is joined thereto by a radius. This end is slotted at 188 and has a tab 190 punched outwardly into the plane of lever 184 to enter the slit 132 in spring 126 which is of the same construction as described above. The other end of the spring is supported by its notches 128 on projections 194 in the same manner as described above. A clearance hole 196 is provided for push rod 46.

The switch blade carries contacts A and B in the same positions as in the preferred form.

The thermostat structure 38A is the same as that described above and shown in FIGURE 9 except that the center arm 140A of the bimetal element is integral with the part 192 connecting the other two arms and is coplanar therewith. A backup strip 198 is welded or riveted thereto. The T-shaped tab 156A is separated from arm 140A and is riveted or otherwise fixed thereto so as to extend beyond the end thereof. The tab is made of electrical insulating material similar to link 118 so that no current can flow to the bimetal element from 41A through this connection.

Otherwise the construction and operation of the structures shown in FIGURE 11 is substantially the same as the preferred form and need not, therefore, be again described.

It is obvious that various changes may be made in the form, structure and arrangement of parts of the specific embodiments of the invention disclosed herein for purposes of illustration, without departing from the spirit of the invention. Accordingly, applicant does not desire to be limited to such specific embodiments but desires protection falling fairly within the scope of the appended claims.

I claim:

1. An internal combustion engine control system including an electric motor pump, electric engine starting means, a source of electric current and a starting switch connected to said source, means, including a normally open first switch, for connecting said motor pump to said source for energization thereby, means, including a normally open second switch, for connecting engine starting means with said starting switch, a time delay mechanism for closing said second switch, including a thermally responsive element and an electric heater therefor, a norit mally closed third switch to supply electricity to said heater from said starting switch and means operable by predetermined response to said element to said heater, for closing said second switch and opening said third switch, to energize said starting motor and deenergize said heater.

2. The structure defined by claim 1 which includes conductors capable of carrying relatively high amperage current, connecting said starting switch directly with said starting means through said second switch.

3. The structure defined by claim 1 wherein said time delay mechanism includes ambient temperature responsive compensating means connected with said thermally responsive element so as to nullify the effects of ambient temperature on said element, said compensating means serving to maintain the time delay in closure of said sec- ,ond switch substantially constant over a wide range of ambient temperatures.

4. The structure defined by claim 1 wherein said time delay mechanism includes additional thermally responsive means, mounted for exposure to substantially ambient temperature, means connecting said two thermally responsive means in compensating relation for maintaining the delay in closure of said second switch substantially constant over a wide range of ambient temperatures.

5. The structure defined by claim 1 wherein said means for closing said first switch includes a solenoid having a magnet coil connected to said source through said starting switch and an armature movable by said coil when the latter is energized, for closing said first switch.

6. The structure defined by claim 1 wherein said means forclosing said first switch includes a solenoid connected for energization by said starting switch and which includes oil pressure responsive means, operable by said engine, for holding said first switch closed.

7. In a switching apparatus, the combination of a body, a normally open first switch mounted on said body, a solenoid mounted on said body to close said first switch when the solenoid is energized, a fluid pressure device mounted on said body, and including means responsive to a rising fluid pressure for closing said first switch, a normally open second switch mounted on said body, a first thcrmoresponsive element adapted to move substantially the same predetermined distance in response to a predetermined change in its temperature, heating means for said element, switch actuating means connected for operation by said element to close and open said second switch as said element is heated by said element and is thereafter cooled and ambient temperature responsive compensating means, connected with said elementto prevent said element from actuating said switch actuating means in response to changes in ambient temperature.

8. The structure defined by claim 7 which includes a normally closed third switch in circuit with said heating means and connected for operation by said switch actuating means, so as to open when said secondswitch is closed.

9. The structure defined by claim 8 wherein said switch actuating means includes a trip mechanism for closing and opening said second and third switches substantially instantaneously.

10. The structure defined by claim 7 wherein said switch actuating mechanism comprisesa movably mounted switch blade, a switch actuating lever, a resilient, over centering member connecting said blade and lever, means mounting said lever for movement to opposite sides of ,a center position with respect to said blade and serving to tension said member during movement to said center position, said member serving to move the blade substantially instantaneously as said lever moves past said center position, and means connecting said element to move said lever.

11. The structure defined by claim 10 wherein said resilient member comprises a U-spn'ng having oneleg 12. The structure defined by claim 7 wherein said thermoresponsive element comprises a first flat bimetal arm and said compensating means comprises a second flat bimetal arm, means connecting the arms at one end so that they extend in substantially parallel, spaced, edge to edge relation, said arms being arranged so as the warp correspondingly in response to the same temperature change, meanstfor fixedly mounting the other end of said second arm on said body and means for connecting the other end of said first arm with said switch actuating means.

13. The structure defined by claim 7 wherein said thermoresponsive element comprises a first bimetal arm and said compensating means comprises a second bimetal arm, means connecting the arms at one end so as to dispose them to extend in substantially parallel, spaced, edge to edge relation, said arms being arranged so as to warp correspondingly in response to the same temperature change, means for fixedly mounting the other end of said second arm on said body, an actuating mechanism for said second switch including switch blade mounted for movement between two positions, a switch actuating lever, a resilient, over centering member connecting said blade and lever, means mounting said lever for movement to opposite sides of a center position with respect to said blade and serving to tension said member during movement to said center position, said member serving to move said blade substantially instantaneously from one to the other of its positions as said lever is moved past said center position and means connecting said lever for movement by the other end of said first bimetal arm.

14. The structure defined by claim 13 wherein said switch blade includes oppositely mounted contacts, first and second fixed contacts arranged for engagement by said firstmentioned contacts respectively, as said blade is moved between said positions, a heating coil mounted on said first arm, means connecting said coil in series with one of said blade contacts and said first fixed contact, said arms and said switch actuating mechanismand being constructed to hold said last mentioned contacts closed so long as saidarms are at ambient temperature.

15. The structure defined by claim 14 wherein said second fixed contacts are disposed so as to be short circuited by the other contact of said blade, for controlling an external circuit. 7

16. The structure defined by claim 7'wherein said second switchis disposed in said body, between said first switch and said fiuid pressure device, said ,element and switch actuating means defining an aligned passage, and a push rod extending from said fluid pressure device, through said passage into actuating relation with said first switch.

17. In a switching apparatus the combination of a body, a number of oppositely disposed contacts, a switch blade mounted for movement between said contacts, a switch actuating lever mounted substantially parallel with said blade for movement to opposite sides of a center position with respect to said blade, aresilient overcentering member connecting said blade and lever andpivotally mounted on each, said lever serving to tension said member as said lever moves toward its centered position, said member acting to move said blade from the contacts on one side to those on the other side substantially instantaneously as said lever'moves past its center position, an ambient temperature compensating thermostatic structure comprising a thermoresponsive element having first and second substantially flat, parallel, bimetal arms disposed inv edge to edge spaced relation, means for joining the arms atone end, means forfixedly mounting the other end of said second arm on said body, means for changing the temperature of one arm and means connecting the other end ofrsaid first arm to actuatesaid lever. I

18. The structuredefinedbyclaim 17 wherein vsaid first and second arms coact to hold said other end of said first arm in a substantially predetermined position relative to said actuating lever throughout a range of ambient temperatures and wherein said lever and member occupy one of two overcenter positions to hold the contacts on one side of said blade closed when said end of said first arm occupies said predetermined position, a heating coil for one of said arms, said coil being in circuit with said closed contacts so as to be deenergized when said contacts are opened, said first arm acting to move said switch actuating lever to its other overcenter position when said one of said arms is heated to a predetermined degree above ambient temperature.

19. The structure defined by claim 18 which includes a source of power and a manually operable switch for connecting said source with said blade for energizing said coil at will when said contacts are closed.

20. The structure defined by claim 19 which includes means for connecting said manually operable switch for 1'4 connecting said source to one of the other contacts for supplying power to an external circuit at will when said other contacts are closed.

References Cited in the file of this patent UNITED STATES PATENTS 2,370,249 Korte Feb. 27, 1945 2,480,538 Barr Aug. 30, 1949 2,565,984 Newman Aug. 28, 1951 2,581,705 =Riche Ian. 8, 1952 2,769,890 Hallerberg et a1 Nov. 6, 1956 2,798,131 Collier July 2, 1957 2,781,485 Slocum Feb. 12, 1957 2,820,130 Dadson Jan. 14, 1958 2,833,889 Boddy May 6, 1958 2,846,538 Hager Aug. 5, 1958 2,864,357 Howard Dec. 16, 1958 2,897,318 Finch July 28, 1959 

